Mast construction



United States Patent 3,112,015 MAST CONSTRUCTION Harry M. Anderson,Strathroy, Ontario, Canada, assignor to Beatty Bros. Limited, Fergus,()ntario, Canada, a corporation of Canada Fiied Feb. 15, 1960, Ser. No.8,559 1 Claim. (Cl. 18913) This invention relates to a mast constructionand in particular to a guye'd mast or tower used for radio transmissionor for supporting communication antennas.

One type of mast used for the foregoing purpose is disclosed in CanadianPatent No. 501,819, granted April 27, 1954. The present inventionrelates to improvements in the type of mast shown therein.

Since the wind load acting on the mast structure governs the height andantenna load rating of the mast structure, it one of the objects of thepresent invention to provide a rnast structure which will keep the windarea of the mast to a minimum.

To attain this objective, the upright members or legs are joinedtogether by formed diagonal braces so that the diagonal braces carry thewind load reactions. Such a construction eliminates the need forconventional horizontal struts heretofore employed. In carrying out theinvention, the location of the diagonal braces on each face of the mastis identical so that the uprights are supported between the diagonalbrace connection points on one face by the diagonal braces on theadjacent side, and similarly throughout the mast structure.

Another object of the invention is to provide a means for attaching theguyed cables to the corners of the mast or tower so that, when the maststructure tends to rotate axially due to eccentric loadings on thestructure, the g-uyed cable tension will counteract any tendency of thestructure to rotate axially.

Other features and advantages or" the invention will be apparent fromthe following description and the accompanying drawings which illustratean embodiment of the same.

FIGURE 1 is a fragmentary perspective view of the adjacent ends of twosections which are 'used to build a mast structure, each section havingthree upright members.

FIGURE 2 is a side elevation of a mast section structure having fourupright members, the figure being on a smaller scale than FIGURE 1.

FIGURE 3 is a plan view of a four sided mast structure shown in FIGURE2.

FIGURE 4 is a fragmentary plan view showing one of the guying bailsattached adjacent the top of upright.

FIGURE 5 is a perspective view of guy cable bail.

Referring now to the drawings, the same show the upper end of a mastsection and the lower end of a mast section 11. Each must section issimilarly constructed and preferably of approximately ten feet in lengthwhich makes a very convenient size of section for handling.

In FIGURE 1, the section 10, and likewise the section 11, are formed ofthree uprights 12, :13 and 14, spaced apart to form a triangular shapedmast in cross section. The legs 12, 13 and 14, are joined together bydiagonal braces 15, the diagonal braces connecting each face of the mastfollow a zig-zag pattern with all the braces joining the three facesregister-ing with each other whereby the diagonal braces carry the windload reactions thus eliminating the need for conventional horizontalstruts. The diagonal braces, as will be seen from the drawings,connecting the legs of each face of the mast structure 3,1 12,615Patented New. 26, 1963 are identical so that the uprights are supportedbetween the diagonal brace connection point in one face by the diagonalbraces on the adjacent side, and similarly throughout the maststructure. This staggered bracing, besides reducing the unsupportedlength of the uprights for maximum strength, makes for easier connectionof the diagonal braces since interference from adjacent members has beeneliminated. As will be seen from FIG- URE l, the diagonal bracing whichconnects the adjacent faces of the legs, for example, of the legs 12 and14, form a zig-zag pattern from the the bottom to the top of the legs.The diagonal braces can be secured to the legs by bolting, riveting orwelding, being accessible to take fa'bricational tools.

A further feature of the invention relates to the specific shape of thediagonal braces. It will be seen that one end, in this case the lowerend, of each brace is bent so that the portion adjacent the upright isperpendicular thereto, said portion being indicated by the numeral 16.Steps are thus for-med at each connection point which aid in climbingthe mast structure and dispenses with the necessity of a ladder. Thediagonal portion of the brace also forms a support for the foot of theperson climbing the mast and thus reduces the hazard of the footslipping off the step.

The upper end of each section has the uprights joined together by meansof cross-bars 17, 18 and 19, the crossbars being disposed substantiallyat right angles to the uprights and connected thereto inwardly of theupper ends. The cross-bars provide a member capable of receiving theguyed cables of the guyed cables bail as hereinafter described.

The guying of the mast consists of a guy bail 20 which is V-shaped, thevertex of the V being formed to suit the cable thimble 21 of the cable26. The leg ends 22, 23 are turned-in at an angle that will allow thebail to swing vertically when installed to suit various guy cableslopes. The angle of the V is such that the bail has tospring into thematching holes formed in the members, 17, '18, 19, respectively, thematching holes being formed adjacent each corner post so that the legsof the bail will straddle its respective post.

The bails are secured in their respective matching holes in the members17, 18, 19 either by threading the leg ends 22, 23, and using nuts asshown in FIGURE 4, or by drilling holes in the ends and using cotterpins 24, 25, as shown in FIGURE 5.

The bail is self-aligning relative to the guy cable pull, the formedlegs of the bail engaging the mast in a shearing fashion. When the maststructure tends to rotate axially, due to eccentric loading on thestructure, the bail acting as an A frame together with the guy cabletension acting from the vertex of the V bail, counteracts rotation. Allguys connect to the mast structure by means of the bails so thatstraightness is maintained throughout the full height of the mast ortower providing maximum cornpressive loading with torsional fatigue iseliminated.

In FIGURES 2 and 3, a mast having four faces is illustrated. Itsconstruction is identical with that shown and described with referenceto FIGURES l, 4 and 5, the only difference being that it has four facesand therefor four upright legs instead of the three faces and threeupright legs as in FIGURE 1.

What I claim as new and desire to protect by Letters Patent of theUnited States is:

In a sectional mast formed of a plurality of interconnected superposedunits, each unit comprising at least three parallel upright corner postsin spaced apart relationship to form a geometric figure in crosssection, cross bars joining the posts into a unitary structure, saidbars being arranged substantially at right angles to the posts and beingsubstantially coplanar to each other, and means inhibiting torsionalmovement of the mast in its erected position, said means comprising aV-shaped bail, each side of the V terminating in an inturned extensionforming a pivot whereby the legs of a bail are pivotally attached tocross rnem'bers disposed on opposite sides of its respective post and ananchored cable, in tension, afiixed to said V-shaped bail.

References Cited in the file of this patent UNITED STATES PATENTSFOREIGN PATENTS Great Britain Apr. 24, 1944

